Semaglutide vs tirzepatide: what is the difference?
Short answer
Semaglutide acts on one incretin receptor, GLP-1; tirzepatide acts on two, GIP and GLP-1. Both are once-weekly injections with large randomized trials behind the branded drugs, and they have been compared head to head in type 2 diabetes and in obesity. Both share the same main cautions. The compounded versions prescribed here are not FDA-approved; which one fits you is a provider decision.
| Key difference | Semaglutide targets the GLP-1 receptor; tirzepatide targets both GIP and GLP-1 |
|---|---|
| Semaglutide | GLP-1 receptor agonist; branded as Wegovy, Ozempic and Rybelsus |
| Tirzepatide | Dual GIP and GLP-1 receptor agonist; branded as Zepbound and Mounjaro |
| Head-to-head trials | SURPASS-2 (type 2 diabetes, 2021) and SURMOUNT-5 (obesity, 2025), both on branded products |
| Schedule | Both once-weekly subcutaneous injections, stepped up gradually by the provider |
| Regulatory status | Compounded versions of both are not FDA-approved; the branded drugs are |
| Study type | Sources |
|---|---|
| Human clinical trials | 4 |
| Other human studies | 0 |
| Animal and lab studies | 0 |
| Review articles | 0 |
How do semaglutide and tirzepatide work differently?
Semaglutide and tirzepatide both mimic incretins, the hormones the gut releases after a meal that act on insulin release, appetite signaling and how quickly the stomach empties. Semaglutide mimics one of them, GLP-1. Tirzepatide is a single molecule that activates both the GLP-1 receptor and the GIP receptor, which is why it is called a dual agonist.
Why adding GIP matters is still being worked out. The practical point is that the two are different drugs with different trial programs, not two strengths of the same thing, and switching from one to the other is a new prescription rather than a dose change.
What do the head-to-head trials show?
Semaglutide and tirzepatide have been compared directly in two published randomized trials, both run on the branded products. SURPASS-2, published in 2021, compared them in adults with type 2 diabetes, with blood-sugar control as the main measure. SURMOUNT-5, published in 2025, compared them in adults with obesity who did not have diabetes, with change in body weight as the main measure; on that primary measure, the tirzepatide group came out ahead on average.
A trial average is not a forecast for one person. Responses vary widely within both groups in every trial, tolerability differs between people, and none of these trials used compounded medication. That is why the choice is made by a provider who knows your history, not from a league table.
| Semaglutide | Tirzepatide | |
|---|---|---|
| Receptors | GLP-1 | GIP and GLP-1 |
| Branded drugs | Wegovy, Ozempic, Rybelsus | Zepbound, Mounjaro |
| Key trials (branded) | STEP 1 (obesity), SELECT (cardiovascular) | SURMOUNT-1 (obesity) |
| Compared head to head | SURPASS-2 and SURMOUNT-5 | SURPASS-2 and SURMOUNT-5 |
| Schedule | Once weekly, stepped up gradually | Once weekly, stepped up gradually |
| Compounded version | Not FDA-approved | Not FDA-approved |
Get Compounded Tirzepatide prescribed, pre-mixed
Do semaglutide and tirzepatide have the same side effects?
Semaglutide and tirzepatide share the same main cautions in their labeling: a boxed warning about thyroid C-cell tumors seen in rodents, which rules out people with a personal or family history of medullary thyroid carcinoma or MEN 2, and warnings about pancreatitis and gallbladder problems. The most common side effects of both are stomach-related, such as nausea, and are the reason both are started low and raised in steps.
Tirzepatide's labeling also notes that it can reduce the effect of oral contraceptives around the start and each step up, which is one of the details a provider covers at intake.
How much do semaglutide and tirzepatide cost through Peptides.build?
Compounded semaglutide and compounded tirzepatide are priced as flat plans that include the provider review, compounding and cold-chain shipping, with no separate membership fee. Tirzepatide costs more than semaglutide on every plan. The current monthly, 3-month, 6-month and 12-month prices are on each protocol page and are the same at every strength the provider prescribes.
Which one is right for me?
Which of semaglutide or tirzepatide fits is a provider's decision, made from your history, your other medications, how you have responded to either before and what you are trying to achieve. Neither is prescribed without that review. If a provider decides neither is appropriate, you are not charged.
Prescribed Semaglutide and tirzepatide vs research peptides: what is different?
Prescribed Semaglutide and tirzepatide are not research chemicals. They are prescription medications: a licensed US provider reviews your intake first, and a licensed 503A pharmacy compounds each one for you by name. Vials sold online as “research use only” skip both steps. What you pay for here is that review, a pharmacy you can name, and a label that says what is in the vial.
A research seller’s certificate of analysis is a document the seller controls: it chooses the lab and the sample, and a PDF can be reused, edited or re-dated. No regulator checks it.
| Point | Prescribed through Peptides.build | Research use only |
|---|---|---|
| Access | Online intake reviewed by a licensed US provider; prescribed only when appropriate. | No prescription and no clinical review of whether it suits you. |
| How it's labeled | A prescription medication compounded for you by name. | Commonly sold labeled “research use only, not for human consumption.” |
| Who prepares it | A licensed 503A US compounding pharmacy under state and federal oversight. | Unregulated suppliers, often with no verifiable chain of custody. |
| Testing | Third-party tested. | Certificates of analysis are self-reported when provided at all. |
| Purity and identity | Prepared to a prescription for a specific patient. | Purity, strength, and even identity are unverified by any independent party. |
This compares two care models, not two products. Compounded medications are not FDA-approved, and we do not claim otherwise. What a prescription adds is a licensed provider deciding whether a protocol is appropriate for you and a licensed pharmacy preparing it. Read the full guide to research vs prescription peptides.
Semaglutide vs tirzepatide FAQ
Is tirzepatide stronger than semaglutide?
In the SURMOUNT-5 head-to-head trial of the branded products in adults with obesity, the tirzepatide group lost more weight on average. That is a group average, not a prediction for one person, and the trial did not use compounded medication.
Can I switch from semaglutide to tirzepatide?
Switching is a new prescription, not a dose change, because they are different molecules. A provider decides whether and how to switch and at what strength to restart.
Are compounded semaglutide and tirzepatide FDA-approved?
No. Both molecules are FDA-approved as branded drugs, semaglutide as Wegovy, Ozempic and Rybelsus and tirzepatide as Zepbound and Mounjaro. The compounded versions are not FDA-approved.
Do they have the same side effects?
Largely. Both carry a boxed warning about thyroid C-cell tumors in rodents and warnings about pancreatitis and gallbladder problems, and both most often cause stomach side effects such as nausea, which is why both are stepped up gradually.
Can I take both at the same time?
No. They act on the same receptor system and are not prescribed together.
Compounded Tirzepatide through Peptides.build
A licensed US provider reviews a short online intake and decides whether a protocol is appropriate. A US 503A pharmacy prepares it already reconstituted, labels the concentration and ships it cold-chain. Dosing is set by the provider and is not published on this site.
Start your Compounded Tirzepatide visit · from $118/moReferences
- Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). New England Journal of Medicine, 2025. doi:10.1056/NEJMoa2416394Study type: Randomized controlled trial (head to head, obesity)
- Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2). New England Journal of Medicine, 2021. doi:10.1056/NEJMoa2107519Study type: Randomized controlled trial (head to head, type 2 diabetes)
- Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). New England Journal of Medicine, 2021. doi:10.1056/NEJMoa2032183Study type: Randomized controlled trial
- Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine, 2022. doi:10.1056/NEJMoa2206038Study type: Randomized controlled trial
Citations are listed with their study type so the evidence can be weighed. Review articles summarize other studies; animal and in vitro findings do not describe outcomes in people.
This article is educational and is not medical advice. The compounded versions discussed here are not FDA-approved; compounded medications are not FDA-approved. No results are implied or guaranteed. Talk to a licensed provider about your own history before starting any protocol.